Process control systems, like those used in chemical, petroleum or other processes, typically include one or more centralized or decentralized process controllers communicatively coupled to at least one host or operator workstation. The process controllers are also typically coupled to one or more process control and instrumentation devices such as, for example, field devices, via analog, digital or combined analog/digital buses. Field devices, which may be valves, valve positioners, switches, transmitters, and sensors (e.g., temperature, pressure, and flow rate sensors), are located within the process plant environment and perform functions within the process such as opening or closing valves, measuring process parameters, increasing or decreasing fluid flow, etc. Smart field devices such as field devices conforming to the well-known FOUNDATION™ Fieldbus (hereinafter “Fieldbus”) protocol or the Highway Addressable Remote Transmitter (HART®) protocol may also perform control calculations, alarming functions, and other control functions commonly implemented within the process controller.
The process controllers, which are typically located within the process plant environment, receive signals indicative of process measurements or process variables made by or associated with the field devices and/or other information pertaining to the field devices, and execute controller applications. The controller applications implement, for example, different control modules that make process control decisions, generate control signals based on the received information, and coordinate with the control modules or blocks being performed in the field devices such as HART® and Fieidbus field devices. The control modules in the process controllers send the control signals over the communication lines or signal paths to the field devices to control the operation of the process.
Information from the field devices and the process controllers is typically made available to one or more other hardware devices such as operator workstations, maintenance workstations, personal computers, handheld devices, data historians, report generators, centralized databases, etc., to enable an operator or a maintenance person to perform desired functions with respect to the process such as, for example, changing settings of the process control routine, modifying the operation of the control modules within the process controllers or the smart field devices, viewing the current state of the process or of particular devices within the process plant, viewing alarms generated by field devices and process controllers, simulating the operation of the process for the purpose of training personnel or testing the process control software, and diagnosing problems or hardware failures within the process plant.
While a typical process plant has many process control and instrumentation devices such as valves, transmitters, sensors, etc. connected to one or more process controllers, there are many other supporting devices that are also necessary for or related to process operation. These additional devices include, for example, power supply equipment, power generation and distribution equipment, rotating equipment such as turbines, motors, etc., which are located at numerous places in a typical plant. While this additional equipment does not necessarily create or use process variables and, in many instances, is not controlled or even coupled to a process controller for the purpose of affecting the process operation, this equipment is nevertheless important to, and ultimately necessary for proper operation of the process.
As is known, problems frequently arise within a process plant environment, especially within a process plant having a large number of field devices and supporting equipment. These problems may be broken or malfunctioning devices, logic elements, such as software routines, residing in improper modes, process control loops being improperly tuned, one or more failures in communications between devices within the process plant, etc. These and other problems, while numerous in nature, generally result in the process operating in an abnormal state (i.e., the process plant being in an abnormal situation) which is usually associated with suboptimal performance of the process plant.
Additionally, many field devices, and especially smart field devices, include diagnostic data of interest to operators and maintenance personnel. Some such diagnostic data may include whether the device is in service (i.e., device state information), a calibration due date, various device alarms and alerts etc. Other such data includes information specific to the device, the device type, the manufacturer, or the process control system in which the device is operating. Still other diagnostic data includes processed statistical data originating within the field device. For example, the field device may be equipped or programmed with one or more statistical processing modules (SPMs) that collect and process data from one or more sensors within the field device.
Operator workstations, which are typically connected to the process controllers through communication connections such as a direct or wireless bus, Ethernet, modem, phone line, and the like, have processors and memories that are adapted to run software, such as the DeltaV™ and Ovation® control systems, sold by Emerson Process Management. These control systems have numerous control module and control loop diagnostic tools. Maintenance workstations may also be communicatively connected to the process control devices via object linking and embedding (OLE) for process control (OPC) connections, handheld connections, etc. The workstations typically include one or more operator applications designed to provide an operator a user interface for controlling the operation, and one or more maintenance and/or diagnostic applications designed to provide an interface that allows an operator to view maintenance alarms and alerts generated by field devices within the process plant, to test devices within the process plant, and to perform maintenance activities on the field devices and other devices within the process plant. Diagnostic applications have also been developed to diagnose problems within the supporting equipment within the process plant.
Commercial software such as the AMS™ Suite: Intelligent Device Manager from Emerson Process Management enables communication with and stores data pertaining to field devices to ascertain and track the operating state of the field devices. See also U.S. Pat. No. 5,960,214, entitled “Integrated Communication Network for use in a Field Device Management System.” In some instances, the AMS™ Suite: Intelligent Device Manager software may be used to communicate with a field device to change parameters within the field device, to cause the field device to run applications on itself such as, for example, self-calibration routines or self-diagnostic routines, to obtain information about the status or health of the field device, etc. This information may include, for example, status information (e.g., whether an alarm or other similar event has occurred), device configuration information (e.g., the manner in which the field device is currently or may be configured and the type of measuring units used by the field device), device parameters (e.g., the field device range values and other parameters), etc. Of course, a maintenance technician may use this information to monitor, maintain, and/or diagnose problems with field devices.
Similarly, many process plants include equipment monitoring and diagnostic applications such as, for example, the Machinery Health® application provided by CSI Systems, or any other known applications used to monitor, diagnose, and optimize the operating state of various rotating equipment. Maintenance personnel usually use these applications to maintain and oversee the performance of rotating equipment in the plant, to determine problems with the rotating equipment, and to determine when and if the rotating equipment must be repaired or replaced. Similarly, many process plants include power control and diagnostic applications such as those provided by, for example, the Liebert and ASCO companies, to control and maintain the power generation and distribution equipment. It is also known to run control optimization applications such as, for example, real-time optimizers (RTO+), within a process plant to optimize the control activities of the process plant. Such optimization applications typically use complex algorithms and/or models of the process plant to predict how inputs may be changed to optimize operation of the process plant with respect to some desired optimization variable such as, for example, profit.
These and other diagnostic and optimization applications are typically implemented on a system-wide basis in one or more of the operator or maintenance workstations, and may provide preconfigured displays to the operator or maintenance personnel regarding the operating state of the process plant, or the devices and equipment within the process plant. Typical displays include alarming displays that receive alarms generated by the process controllers or other devices within the process plant, control displays indicating the operating state of the process controllers and other devices within the process plant, maintenance displays indicating the operating state of the devices within the process plant, etc. Likewise, these and other diagnostic applications may enable an operator or a maintenance person to retune a control loop or to reset other control parameters, to run a test on one or more field devices to determine the current status of those field devices, or to calibrate field devices or other equipment.
The variation between field devices (and other process control equipment) generally requires specialized maintenance and diagnostic software to take full advantage of the available diagnostic data. The specialized software downloads information from associated process control equipment upon request or need, potentially delaying communication of other data and consuming communication bandwidth that the system could otherwise use for transmitting and receiving real-time process signals. That is, diagnostic data and other process control data are not always readily available for use by a control or display application, as it often requires a third-party application to read and return the data to the control system.